I assume this is for NTFS deduplication. With Windows Server 2016 build 1709, deduplication was added to ReFS: https://docs.microsoft.com/en-us/window ... erver-1709
Is this a supported, and/or recommended, configuration with Veeam? Does the same configuration apply to ReFS, ref the Veeam blogpost?

Starting Update 3, Veeam B&R disables block cloning on ReFS volumes with built-in deduplication enabled (unless the repository is CIFS, where we cannot check). The two features cannot be used simultaneously.

The best answer is, it depends. And I know that sounds like a copout, but it really does.

If you perform Active Full Backups then stick with deduplication as that will catch duplicate blocks across all files on the volume. Remember, Veeam dedupe only occurs within a single backup file, such as data within a single VBK and not across multiple backup files for the same job. ReFS won't give much, if any, benefit when performing Active Fulls.

However, if you are performing Synthetic Fulls, then ReFS is a good candidate as it provides much faster creation of the synthetic full VBK file. Be sure to check the Veeam B&R console logs to confirm the job is using Fast Clone to perform the synthetic operation. This indicates that Veeam detected the backup repository is ReFS and is leveraging it for your synthetic full creation, which dramatically reduces the time to create the new VBK.

If you saw this week's Veeam Digest you will see that Microsoft have approved ReFS for use on SAN volumes (iSCSi/FC/FCoE) as long as the devices in the path, including the storage array are in the Windows Server Catalog (https://www.windowsservercatalog.com/). Previously Microsoft would only support ReFS when using on direct-attached storage. To quote Gostev in the email, "ReFS is in fact fully supported on ANY storage hardware that is listed on Microsoft HCL". You can read about ReFS here: https://docs.microsoft.com/en-us/window ... s-overview

I work for NetApp so I'm happy to see that all of our current systems are fully supported by Microsoft with Windows Server 2016 so we can use ReFS for Backup Repositories and then use ONTAP's dedupe to get the best of both worlds ... although if you were using ONTAP you would be best to leverage ONTAP snapshots and SnapMirror for complete protection whilst still retaining Veeam's features like application-aware processing and SureBackups. But it's great to have the options now.

Essentially, the Veeam backup repository is a VM running on a Hyper-V host. Inside the VM you run ReFS with Fast Clone, and on the host you run NTFS with deduplication (or eventually ReFS with deduplication). I was holding off on this until the ReFS issues have been sorted out, but with the latest updates looking promising, I'm going to start working on moving my repositories into new 2016 VMs and see how it works.

nmdange wrote:Essentially, the Veeam backup repository is a VM running on a Hyper-V host. Inside the VM you run ReFS with Fast Clone, and on the host you run NTFS with deduplication (or eventually ReFS with deduplication)

I'd be very interested in the IOPs this results in. I've Deduped CSV volumes in the past with much success. However there is a corresponding increase in read IOPs

foggy wrote:Starting Update 3, Veeam B&R disables block cloning on ReFS volumes with built-in deduplication enabled (unless the repository is CIFS, where we cannot check). The two features cannot be used simultaneously.

Be aware that REFS+DEDUPE is not possible for Windows Server 2016 Version 1607 which is an LTSC release.
For REFS+DEDUPE you need to have Version 1709 which is Semi Annual channel release. In place upgrades from 1607 to 1709 are not possible.